JPH02190833A - Diaphragm device - Google Patents

Abstract

PURPOSE:To prevent hunting with high luminance by setting a filter whose transmittivity changes so that its transmittivity on a side where a diaphragm becomes small may be low. CONSTITUTION:The part 2a of the filter 2 which is set at a position protruding from the stop aperture end 3a of a stop blade 3 in an optical axis center direction A by a fixed amount is a part used as the filter and is formed so that the transmittivity such as alpha1, alpha2 and alpha3 may change stepwise respectively between 0-x1, x1-x2 and x2-x3 which are the distances from an end face to the optical axis center direction A. In the part 2a, each transmittivity changes in order alpha1>alpha2>alpha3. The transmittivity is set so that its may be smaller on the side of the end face x3 of the aperture part of the stop blade 3. Thus, the motion of the blade corresponding to the change of F-value is drastically improved and the function for preventing hunting in the case of high luminance is enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aperture device installed in a photographic device such as a video camera, and in particular to a filter such as an ND (221 Toral Density) for adjusting the amount of light. The present invention relates to an improvement of a diaphragm device having the present invention.

[Prior art] As known from Utility Model Application No. 60-23697, in a conventional aperture device, an ND filter is pasted or arranged to cover an aperture diameter of about F8 to F11 for small aperture correction. ing.

[Problems to be Solved by the Invention] However, in the conventional example described above, since an ND filter is used, the light intensity correction is uniform for apertures smaller than F8 to F11, resulting in the following drawbacks. Ta.

In other words, the aperture aperture becomes larger by the amount of light reduced by the ND filter, but the aperture blade aperture for each F-number aperture is
Since there is no big difference compared to the one without a D filter, hunting occurs at high brightness.

[Means for Solving the Problems] According to the present invention, the aperture diameter is prevented from becoming small by installing a filter whose transmittance is uniformly changed so that the transmittance is lower on the side that becomes the small aperture. It is something.

The present invention solves the conventional problems by forming a filter to change the transmittance for adjusting the amount of light.

[Example] Fig. 1 and Fig. 2 show a first embodiment of the present invention, and Fig. 1 is a drawing that best represents the features of the first embodiment.
In the figure, 2 is a filter that limits the amount of transmitted light, 3 is an aperture blade that constitutes the aperture of the aperture, and has an aperture end 3a), and 20 is a filter that controls the amount of transmitted light. This is an adhesive for attaching the filter 2.

A portion 2a of the filter 2 (a region protruding from the end surface of the aperture blade in the optical path direction) installed at a position protruding by a certain amount in the optical axis center direction A from the aperture opening end 3a of the aperture blade 3 is used as a filter. As shown in Fig. 2, the distance from the end face toward the optical axis center direction A is 0-X + +
Transmittance α1.X+~x2x2~X, respectively.
It is formed to change stepwise like α2°α3. The transmittance of each part 2a is α1〉
The transmittance changes in the order α2>α3, and the transmittance is set to be low on the aperture end surface x3 side of the aperture blade 3. For this reason, when the aperture formed by the aperture blade 3 and the other aperture blade (not shown, but the same as the aperture blade 4 in FIG. 7) is completely covered by the filter 2, it becomes normal. In the case of an ND filter, the transmittance is constant, so the movement of the blades with respect to changes in the F value is no different from that without an ND filter after F32, but according to this embodiment, the transmittance of filter 2 is changed in stages. Because of this, the movement of the blades in response to changes in the F value is greatly improved, making it very advantageous against hunting.

Fig. 3 shows an example of the deflection angle characteristics of the drive arm (12) of the FNO and the diaphragm (same type as the diaphragm shown in Fig. 7).
It can be seen that up to F88, the drive arm is only slightly bent. On the other hand, in curve B representing the conventional ND filter, the deflection angle is somewhat expanded compared to curve A, but the change becomes smaller after F44. However, according to the characteristic curve C representing the filter 2 of this embodiment, it can be seen that the deflection angle at a small aperture has been improved to a large extent. For example, when comparing two stages from F44 to F & 8, the difference is 0.0 without a filter.
It is about 8 degrees, about 1.5 degrees with the ND filter, and about 2.5 degrees with the filter of this embodiment. This enlarged deflection angle of the drive arm (12) makes it easier to control the drive unit (5) with a small aperture.
Can hold down the punch jig.

[Example 2] The second example is a filter 2 as shown in FIGS. 4 and 5.
By changing the transmittance of 1 in a curved manner rather than stepwise, it is possible to perform smoother aperture correction.

That is, in the filter 21 shown in FIG. 4, at least the portion 21a located at a position protruding from the aperture aperture D%fi3a toward the optical axis center has a substantially curved transmittance as shown in the graph of FIG. It is something that is changing.

[Example 3 Next, a third embodiment will be described based on FIGS. 6 and 7.

In FIG. 7, reference numeral 1 indicates an aperture base plate which is a stationary structure of the light aperture device, 30.4 indicates an aperture blade that moves relatively along the longitudinal direction of the aperture base plate 1, and 20 indicates the aperture blade 30.
ND filter has almost the same shape as the diaphragm blade 30, but has a shape such that the portion 120c protrudes from the diaphragm blade 30 when overlapped with the diaphragm blade 30; 5 is a motor for driving the diaphragm blades 30 and 4; 6; .7 is the rotating shaft 13 of the motor 5
Drive pins 8, 9, 10.11 installed on the drive arm 12 attached to the diaphragm blade 30.4 and the long groove portions +20b, 120c, 120d of the ND filter 120,
30b, 30c, 30d, 4b, 4c, 4d,
This is a guide pin to guide these movements.

The long groove portion 120b of the ND filter 120 is attached to the drive bin 6.
The long groove portion 30b of the aperture blade 30 is also connected to the guide pin 8.9.
are the long groove portions 120C and 1 of the ND filter 120, respectively.
20d, and the long grooves 30c and 30d of the aperture blade 3o are inserted therein.

The aperture blade 4 has a long groove portion 4b on the drive pin 7 and a guide pin 10. II each has a long groove portion 4c.

4d is inserted from above the aperture blade 30. A lid (not shown) is attached to the top of the aperture blade 4 to prevent the aperture blade from being pulled out.

In the above configuration, when the rotation shaft 13 of the motor 5 rotates clockwise, the drive pin 6 implanted in the drive arm 12
moves to the left in the figure, the drive bin 7 moves to the right in the figure, and accordingly the aperture blades 3o and the ND filter 120 move to the left, and the aperture blades 4 move to the right. An opaque portion 30e of the diaphragm blade 3° and an opaque portion 4e of the diaphragm blade 4 appear above a certain opening of the diaphragm base plate 1, and the amount of light passing through the opening 1a is reduced.

Conversely, when the rotating shaft of the motor 5 rotates counterclockwise, the aperture blades 3° and the ND filter 120 move to the right in the figure, and the aperture blades 4 move to the left in the figure, due to the opposite effect to that described above. Then, the aperture blades 3o are placed on the aperture la of the aperture base plate 1.
The opening 30f of the diaphragm 4 and the hole 4f of the diaphragm 4 come out, and the amount of light passing through the opening 1a is increased.

As described above, the positions and dimensions of each long groove of the ND filter 120 are the same as the positions and dimensions of the corresponding long grooves of the aperture blade 30, and the positions and dimensions of each of the long grooves of the ND filter 120 and the aperture blade 30 are the same. Since the long grooves are fitted into the same drive bottle and guide pin, the ND filter 120 performs exactly the same operation as the aperture blades 30. Therefore, when the ND filter 120 is overlapped with the aperture blades 30, During the above operation, the positional relationship of the protruding portion 120c used as a filter with respect to the aperture blade 30 is always kept constant.

Here, the ND filter 120 is 1.0 mm toward the center of the optical axis. A plurality of three transmittances α-electron α2. Since it is formed to have a transmittance of α3, the protruding portion 120c also has a transmittance of α1. It is divided into α2α3.

According to this third embodiment, the above-mentioned first. 2nd fruit b'lx
Compared to the example, the ND filter has the same shape as the aperture blades and has a configuration that performs the same operation, so there is no need to glue the ND filter and the aperture blades, and if adhesive is used, the adhesive Problems such as protrusion are eliminated. Also,
The position of the part of the ND filter used as a filter relative to the aperture blade can be determined simply by incorporating it into the aperture position, eliminating positional variations and the assembly process of setting the ND filter and aperture blade in a jig, etc. during bonding. Can be done.

[Effects of the Invention] In the present invention, the transmittance of the filter is not made uniform, but is formed so that the transmittance basically changes toward the center of the optical axis, which eliminates hunting, which was a problem in the past. can be prevented.

In particular, depending on the embodiment, the control characteristics are improved by increasing the amount of change in the deflection angle of the drive section, and the hunting prevention function at high brightness is improved.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the aperture blades of the first embodiment of the present invention, Fig. 2 is a graph showing changes in transmittance of the ND filter of Fig. 1, and Fig. 3 is an aperture using the aperture blades of Fig. 1. A graph showing the vibration color characteristics of the drive arm of the device, Fig. 4 is a perspective view of the aperture blade as the second embodiment, Fig. 5 is a graph showing changes in transmittance of the ND filter in Fig. 4, Fig. 6 is a perspective view of a filter as a third embodiment, and FIG. 7 is an exploded perspective view of a diaphragm device incorporating the filter of FIG. 6. 2.21.120...ND filter, 3.30...
aperture blade.

Claims (5)

[Claims] (1) A plurality of aperture blades that are relatively driven to vary the size of the aperture aperture, and a filter for adjusting the amount of light that is at least partially disposed within the aperture formed by the aperture blades. A diaphragm device, characterized in that the filter is formed to have a plurality of transmittances. (2) A plurality of aperture blades that are relatively driven to vary the size of the aperture aperture, and a filter for adjusting the amount of light that is at least partially disposed within the aperture formed by the aperture blades. A diaphragm device, characterized in that the filter is formed so that its transmittance changes toward the center of the optical axis of the aperture. (3) The aperture device according to claim (2), wherein the filter is set so that the quasi-order transmittance increases toward the center of the optical axis of the aperture. (4) In an aperture blade in an aperture device that is relatively driven to vary the size of an aperture aperture, a filter for adjusting the amount of light is attached to the aperture blade, at least a portion of which is disposed within the aperture aperture. A diaphragm blade characterized in that the filter is formed so that the transmittance changes toward the optical axis center of the diaphragm aperture. (5) In a filter for adjusting the amount of light provided in a diaphragm device having a plurality of diaphragm blades that are relatively driven to vary the size of the diaphragm aperture, at least a portion is located within the aperture formed by the diaphragm blades. What is claimed is: 1. A filter characterized in that the filter is arranged such that the transmittance changes toward the center of the optical axis of the aperture.